How would you judge the winner? After all, the general assumption behind WTA is that someone who reaches 18 centres can routinely defeat every other power, thereby automatically completing all missions.

Surely this wouldn't change the game at all? You just play normally....

Another variant idea: Diplomacy Mafia

2 players are secretly designated the mafia. They are allowed to communicate privately; everyone else is (on their honor) only allowed public press. One of the other 5 players is secretly designated the detective and learns the identity of one player after each even-numbered year's build round.

If both Mafia are still alive after 1910, they win. If that doesn't happen, play continues on until someone gets to 18 or one side is eliminated.

I think that the assassin variant assigns a particular order to eliminating the other parties. And your goal should really be elimination of that party, rather than traditional victory conditions.

What if the game ends as soon as one player is eliminated, and whoever had to take that player out is the winner?

@Xapi- That seems perfect. How would we end the game once a player was eliminated, though?

Also, how would assignments be... assigned?

A third party- non-gamer -would use some random generator to assign each person a country. Switches could be had if one person got themselves.

Another problem. In order that everyone can win, everyone has to have a different target and everyone is also the target of someone. Therefore, any power that attacks anyone is either intentionally helping someone else win (unlikely!) or is attacking their target. Therefore the power's neighbours should protect the power being attacked and prevent the power attacking from growing. There is no way to set up an expansionist alliance, so the result is a trivial 7 way.